1. Field of the Invention
The invention is directed to a pouring device for metallurgic vessels, particularly for steel melts, with slide plates which can be adjusted and slid out again one behind the other in a row under a vessel opening and into which filters can be inserted. The invention further relates an immersion pipe projecting into a mold, and to a method for controlling the outflow quantity.
2. Discussion of the Prior Art
A ceramic filter which can be installed in refractory wearable parts through which a melt flows is known from German reference DE 40 12 093 for refining metallurgic melts, in particular steel melts. In one constructional form, slide plates which carry out a plurality of different functions are constructed as a through-slide closure; individual plates which are adjustable and can be slid out again are arranged on rails one behind the other in a row under a vessel opening.
The discharge closure known from this reference is supposed to make it possible to exchange clogged filters quickly and with reliable operation during the casting operation.
It is disadvantageous in this arrangement that the filter is gradually clogged during the casting operation and the resistance in the pour-out opening continuously increases. The gradual clogging causes a rise in the pressure loss exerted by the filter. This rise must be compensated by the opening of an additional control armature which is in a partly closed position when the filter is completely clear. Regulation of the casting surface level must also take place via this device.
Further, the gradual clogging of the filter causes an increase in the filtering effect, so that when the filter is completely clear the degree of purity of the melt is relatively poor, but is relatively good when the filter is almost stopped up. It is accordingly impossible for the degree of purity of the melt to be maintained constant over a long casting period.
The filter can only be exchanged as a complete structural component part. Exchanging the filter element entails interrupting the supply of melt to the mold. Depending on the duration of this interruption, the casting speed must be appreciably reduced in order to continue the casting operation. Strong turbulence is brought about in the mold when pouring is initiated again, which results in a clear drop in quality of the strand in question.
The object aimed at by the invention is to provide a pouring device for metallurgic vessels in which the molten metal flowing out is filtered in a constant manner accompanied by uniform flow conditions in the immersion pipe.
According to the invention, the immersion casting pipe is closed by a slide plate which has a filter part that is displaceable transverse to the pour-out direction in a manner which can be predetermined and that maintains a constant open through cross section in the immersion casting pipe. For this purpose, the quantity of melt flowing down through the immersion casting pipe is detected and serves at the same time as a measure for the clogging of the filter openings, and the slide plates are displaced in a suitable manner.
Slide plates which have a filter part having openings arranged in the casting direction and which have at least one solid web plate part are used for this purpose. Further, actuators are provided by which the slide plates can be displaced in the conveying direction (x-direction) and, in addition, in the same plane, but perpendicular thereto (i.e., in the y-direction). These actuators communicate, via regulating devices, with measuring elements by which the flow through the immersion casting pipe can be detected.
The clear cross section can be increased or reduced, as desired, during the casting operation by means of the individual parts of the slide plates, the filter part and the solid web part.
The diameter of the openings provided in the filter part is d=0.2 to 1 mm. In an advantageous construction, the openings are slit-shaped with a length-to-width ratio of l/b=5/1 to 8/1.
The device according to the invention enables a constant operating run over optionally long time periods because the filter segments can be exchanged without affecting the operating run.
An additional control armature is not required because the regulating of the casting level in the mold is performed by the filter itself. The possibility of displacing in the x-direction and y-direction is made use of for this purpose, or the filter bores which have already been clogged are used as a closed regulating plate.
Due to the fact that the melt flows out of the filter part of the slide plate uniformly, favorable flow conditions result in the flow channel located below the latter as well as in the mold, which has a positive influence on the steel quality.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.